Editor's Note: This column has been substantially corrected thanks to correspondence from checker expert Al Lyman.

The photo above shows a nasty diagonal crack in the foundation of someone's house. That's going to be an expensive problem but it's best to diagnose and fix it before it gets worse.

As we mentioned in our previous installment from Willie Ryan's Tricks Traps & Shots of the Checkerboard, we're getting toward the end of the book and Willie's examples have turned even more complex than ever. In today's installment, Willie, who lacked powerful 21st century computing capabilities, had a few of his own diagonal cracks in the foundation of his analysis. Still, it's hard to fault such a brilliant man; he was doing everything in his head with no silicon monsters to help him out, and he got it right far more often than not.

Today, we're asking you to repair the cracks, and we understand that that's a tall order indeed. But we think you'll enjoy and benefit from our revised analysis, all of which is attributed to Ed Gilbert's KingsRow computer engine and 10-piece endgame database. Think what Willie would have done with such fabulous tools. No more patching by hand!

9-13	18-9	13-22	1-5	12-16
21-17	5-14	20-16*	11-15	17-13
11-15	24-20---I,4	11-18---O	5-9	18-23
25-21	3-8---J	19-15	8-11	24-20---9
8-11	28-24	10-28	27-24	White
23-18---1	1-6*---K	30-26	4-8	should
6-9---2	23-19*---5	12-19	21-17	win.
26-23---A	15-18---N,6	26-1*---P	8-12	Wm. F.
9-14---B,3	22-15	7-11---7	29-25---8	Ryan.

A---"The orthodox continuation here is: 27-23, 9-14, 18-9, 5-14, 30-25, 1-6, 24-19, etc. While the 26-23 line is not so safe, it is sound enough, and is considerably more productive of wins than the conservative 27-23 development.

B---3-8 is stronger at this point and has been published erroneously as a play to win for black. The following outline charts the course to safety for white:

3-8	32-27*	6-9	23-18	19-23
23-19*	1-6	31-27---G	27-24	2-7
11-16---C	30-26*	7-10	18-15	23-18
18-11	10-15---E	28-24	24-19	1-6
16-23	20-16*	19-28	15-10---H	18-25
27-18	2-1---F	27-24	4-8	7-10
8-15	27-23*	12-19	6-1	13-22
18-11	15-18	24-6	8-11	6-13*
7-16---D	23-14*	28-32	10-6	Drawn.
24-20*	9-25	26-23	11-15	Wm. F.
16-19	29-22	32-27	6-2	Ryan.

C---If the moves are: 9-14, 18-9, 5-14, then the draw is reached with: 30-25*, 11-16, 24-20, 15-24, 28-19,16-23, 27-9,1-5,17-14, 10-26, 31-22, 5-14, 22-17, 13-22, 25-9. Wm. F. Ryan.

D---Abandoned here by P. H. Ketchum without further play. He judged the situation to be strong for black, if not a win. The route to a draw from this point involves instructive analysis.

E---4-8 is a low-pressure alternative and barely gains a draw, viz: 4-8, 27-24*, 2-7, 24-15, 10-19, 22-18*, 13-22, 26-17, 9-13*, 17-14, 6-9*, 29-25, 8-11*, 31-27, 19-23, 27-24, 13-17, 24-19, 17-22, 21-17, 22-29, 17-13, 29-25, 13-6, 23-26, 6-1, 25-21, 1-6, 21-17, 6-10, 5-9, 10-3, 17-10, 3-8, 10-14. Wm. F. Ryan.

F---Or 6-10, 27-24, 9-14, 16-11, 12-16, 31-27*, 5-9, 29-25*, 16-20, 11-7, 2-11, 27-23, 20-27, 23-7, 27-31, 26-23, 31-27, 23-19, 15-24, 28-19, which also produces a draw. Wm. F. Ryan.

G---A more difficult draw may be effected with careful play by 22-18,13-22, 26-17, 9-13, 17-14, 19-23, 18-15, 12-19,15-10, 5-9, 10-3, 9-18, 3-7, 18-22, 7-10, 22-25, 10-15, 4-8, 15-24, 8-12, 24-20, 25-29, 28-24. Wm. F. Ryan.

H---The position is now clearly a draw, but we continue the play to illustrate a fancy as well as feasible finish.

I---White has the best looking board, with virtually all of the winning chances in his favor.

J---The build-up by 4-8, 28-24, 1-6, 23-18 is a creaky combination for black, but 15-19, 23-16, 12-19 will do well; at this point, continue with: 27-24, 10-15* (not 11-15, 22-18*, 15-22, 24-6, 1-10, 32-27 *, etc., as white will win; I have victimized many a player with this scheme) 17-10, 7-14, 30-26, 2-7, 32-27, 4-8, 27-23* (not 22-17, 13-22, 26-10, 7-14, 31-26, 14-18, 26-22, 18-25, 29-22, 1-5, 21-17, 5-9, 17-13, 9-14, 13-9, 14-18, 22-17, 19-23, as black will win. Paul Thompson); 8-12, 23-16, 12-19, 22-17, 13-22, 26-10, 7-14, 31-26*, 14-18, 26-22, 18-25, 29-22, 19-23, 24-19, 15-24, 28-19, 23-26, 22-18, 26-30, 19-16, 30-25, 16-7, 3-10, 21-17, ending in a draw. Wm. F. Ryan.

K---Black's only move to draw. The three alternatives, 1-5, 11-16, and 12-16, all lose in short order as follows:

1-5---L	15-24	10-19	13-17	12-16
30-25*	27-11*	17-10	21-5	31-26
5-9---M	8-15	19-23	30-21	16-19
32-28*	23-19*	10-6*	18-14	26-22
11-16	15-24	23-26	21-17	19-23
20-11	28-19	6-1	14-9	29-25.
7-16	4-8	26-30	17-14	White
24-19*	19-15	22-18	1-6	wins.

L---If the play goes: 11-16, 20-11, 7-16, white triumphs with 23-18, 14-23, 27-11, 8-15, 30-26, 16-20, 17-14, 10-17, 21-14, 20-27, 31-24. Again at L, if 12-16 is the play, white romps home first with: 23-19, 16-23, 27-9, 1-5, 9-6, 2-9, 30-26, 9-14, 26-23, 8-12, 35-19, 14-18, 29-25, 5-9, 32-27, 9-14, 31-26, 4-8, 26-23. Wm. F. Ryan.

M---Against 11-16, 20-11, 7-16, white executes a very unique clean-out and wins with: 23-19*, 16-23, 27-9, 5-14, 22-18*, 14-23, 31-27, 13-22, 25-11, 8-15, 27-11. Wm. F. Ryan.

N---Loses, and white snaps the trap shut with a startling stroke, which has claimed many a champion. I was caught by this one several times before I came to recognize it; and I saw Newell W. Banks entrapped by it as well. The following play at N assures a draw and makes white run hard for home: 6-9*, 30-25*, 11-16, 20-11, 7-23, 27-11, 8-15, 24-19*!, 15-24, 32-28, 24-27, 31-24, 12-16, 24-20, 16-19, 20-16, 4-8, 16-12, 8-11, 12-8, 11-15, 8-3, 19-24, 28-19, 15-24, 3-8, 2-7, 8-12, 24-27 (not 7-11, 22-18!, as white will win), 12-16, 27-31, 16-19, 7-11, 19-15, 10-19, 17-10, 31-27, 10-6, 27-23, 6-1, 19-24, 21-17, 23-26, 25-21, 26-30, 1-6, 11-15, 6-10, 15-19. Wm. F. Ryan.

O---11-20, 19-16, 12-28, 30-26, 10-19, 17-1* is no better, and also loses. The important point is to take the stroke into square one, and not to three, as the ending with the king on square three cannot be scientifically won.

P---White now has a free hand with his king. Black cannot crack the line without the loss of a piece, and subsequently loses because his position deteriorates. Although the stroke following black's 15-18 move at JV has been published several times, I can find no record of it being properly executed. Invariably, white has made the mistake of jumping into square 3 at Note P. I make no claim for the play prior to the shot, but its proper execution, as revealed in this study, as well as its attending formational structures discussed in the notes, are my contributions to an outstanding, brilliant, and practical stroke."

1---30-25 is substantially better here---Ed.

2---4-8 would have been preferable---Ed.

3---While 3-8 can't be called "winning" it certainly gives Black an edge---Ed.

4---Willie's comment is hard to understand as the computer finds this position to be dead even. Perhaps White is stronger in practical over the board play.

5---Why Willie stars this move baffles us; far from winning, it gives Black the advantage! 32-28 was the right move here---Ed.

6---This is not actually a losing move---Ed.

7---8-11 is best; White now has a solid edge---Ed.

8---While White can't be said to have a clear win, 24-20 was correct here. The game is now a draw.---Ed.

9---The game is definitely a draw according to the computer; we don't see Willy's win for White at all---Ed.

Can you demonstrate the draw for Black here? Fix the crack in the problem and then click on Read More to check your solution.

Solution

19-24 9-14 23-27!---10 32-23 15-18!---11 25-22---12 18-25 23-18 28-32 18-15 11-18 14-23 32-27!---13 16-19 32-27 25-30 13-9 30-26! 31-22 24-31 to a clear draw.

10---Black willingly gives back the extra man---Ed.

11---Taking advantage of the weak White piece on 23---Ed.

12---It looks odd, but White forces Black to jump in a favorable manner. Moves like 31-26 or 25-21 or even 13-9 give Black a big advantage and a likely win---Ed.

13---Again forcing White's hand---Ed.